Question

Which one of the following statements in regard to the excretion by the human kidneys is correct?

• A. Distal convoluted tubule is incapable of reabsorbing $HC{O}_3^{-}$.
• B. Ascending limb of loop of Henle is impermeable to electrolytes.
• C. Descending limb of the loop of Henle is impermeable to water.
• D. Nearly 99 per cent of the glomerular filtrate is reabsorbed by the renal tubules.

Answer 1

The correct option is D Nearly 99 per cent of the glomerular filtrate is reabsorbed by the renal tubules.

Ascending limb of loop of Henle are thick walled and impermeable to water. Descending limb of the loop of Henle is thin walled and permeable to water but impermeable to salt and thus indirectly contributes to the concentration of the interstitium. Distal convoluted tubule is a portion between the loop of Henle and the collecting duct system which is capable of reabsorption of $HC{O}_3^{-}$; and selective secretion of hydrogen and potassium ions and ${\mathrm{NH}}_3$ to maintain the pH and sodium-potassium balance in the blood.